Using heterogeneous catalysts to promote the construction of the C–N bond between amines and CO_(2) under mild conditions is a challenge yet.Herein,we synthesized a novel zwitterionic polymer(PDDC)with a cellular str...Using heterogeneous catalysts to promote the construction of the C–N bond between amines and CO_(2) under mild conditions is a challenge yet.Herein,we synthesized a novel zwitterionic polymer(PDDC)with a cellular structure via self-complexation of copolymer bearing both quaternary ammonium cation and carboxylate anion.PDDC was employed as a recyclable catalyst for N-methylation of atmospheric CO_(2) and various amines with hydrosilane as a reductant,affording more than 17 N-methylamines in good to excellent yields(up to 99%)under mild conditions.The behavior of PDDC in the reaction medium was disclosed by using a dynamic light scattering study,revealing that the decreased hydraulic radius of particle size contributes to exposing more active sites and increasing reaction activity.Utilizing a series of designed experiments and density functional theory calculations uncovered the crucial role of the prepared zwitterionic polymer during the reaction procedure of CO_(2) conversion.展开更多
The cucurbit[8]uril (Q[8]) mediated oxidation of benzenedimethanols with o-iodoxybenzoic acid (IBX) inaqueous solution has been investigated, and the results reveal the supramolecular catalysis depends on the electron...The cucurbit[8]uril (Q[8]) mediated oxidation of benzenedimethanols with o-iodoxybenzoic acid (IBX) inaqueous solution has been investigated, and the results reveal the supramolecular catalysis depends on the electronicand geometric structure of substrate. In the cases of o-benzenedimethanol (1a) and m-benzenedimethanol (1b), theIBX oxidation could be obviously enhanced by the addition of Q[8] at different extent. There is no observation ofthe catalytic activity of Q[8] when p-benzenedimethanol (1c) is subjected to the IBX oxidation. The additionamount of Q[8] is discussed herein, and the addition of more than 10% mol catalyst cannot improve the oxidationmuch more. The investigation of host-guest interactions by isothermal titration calorimetry implies the supramolecularcatalysis is related to the formation of complexes between benzenedimethanols and cucurbit[8]uril.展开更多
On August 17,2020,the Academic Seminar on the Research and Compilation of African History in the New Era and the Forum of Young Historians hosted by the Chinese Society of African Historical Studies and organized by t...On August 17,2020,the Academic Seminar on the Research and Compilation of African History in the New Era and the Forum of Young Historians hosted by the Chinese Society of African Historical Studies and organized by the African History Research Office of the Institute of World History,Chinese Academy of Social Sciences was held in Beijing.The conference was conducted online and offline simultaneously.Nearly 80 experts and scholars discussed the topics about how to promote the study of China’s African history and the compilation of Africa’s general history.展开更多
基金This study was financially supported by the Guizhou Provincial S&T Project(Nos.ZK[2022]011 and 2018[4007])the National Natural Science Foundation of China(No.21908033)the Fok Ying-Tong Education Foundation(161030).
文摘Using heterogeneous catalysts to promote the construction of the C–N bond between amines and CO_(2) under mild conditions is a challenge yet.Herein,we synthesized a novel zwitterionic polymer(PDDC)with a cellular structure via self-complexation of copolymer bearing both quaternary ammonium cation and carboxylate anion.PDDC was employed as a recyclable catalyst for N-methylation of atmospheric CO_(2) and various amines with hydrosilane as a reductant,affording more than 17 N-methylamines in good to excellent yields(up to 99%)under mild conditions.The behavior of PDDC in the reaction medium was disclosed by using a dynamic light scattering study,revealing that the decreased hydraulic radius of particle size contributes to exposing more active sites and increasing reaction activity.Utilizing a series of designed experiments and density functional theory calculations uncovered the crucial role of the prepared zwitterionic polymer during the reaction procedure of CO_(2) conversion.
基金the support of National Natural Science Foundation of China(No.21162003)the International Collaboration Project of Guizhou Province(No.[2011]7003)the Natural Science Foundation of Guizhou Province(No.[2008]75).
文摘The cucurbit[8]uril (Q[8]) mediated oxidation of benzenedimethanols with o-iodoxybenzoic acid (IBX) inaqueous solution has been investigated, and the results reveal the supramolecular catalysis depends on the electronicand geometric structure of substrate. In the cases of o-benzenedimethanol (1a) and m-benzenedimethanol (1b), theIBX oxidation could be obviously enhanced by the addition of Q[8] at different extent. There is no observation ofthe catalytic activity of Q[8] when p-benzenedimethanol (1c) is subjected to the IBX oxidation. The additionamount of Q[8] is discussed herein, and the addition of more than 10% mol catalyst cannot improve the oxidationmuch more. The investigation of host-guest interactions by isothermal titration calorimetry implies the supramolecularcatalysis is related to the formation of complexes between benzenedimethanols and cucurbit[8]uril.
文摘On August 17,2020,the Academic Seminar on the Research and Compilation of African History in the New Era and the Forum of Young Historians hosted by the Chinese Society of African Historical Studies and organized by the African History Research Office of the Institute of World History,Chinese Academy of Social Sciences was held in Beijing.The conference was conducted online and offline simultaneously.Nearly 80 experts and scholars discussed the topics about how to promote the study of China’s African history and the compilation of Africa’s general history.
